forked from tdewolff/canvas
/
sfnt_layout.go
647 lines (571 loc) · 17.9 KB
/
sfnt_layout.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
package font
import "fmt"
type langSys struct {
requiredFeatureIndex uint16
featureIndices []uint16
}
type scriptList map[ScriptTag]map[LanguageTag]langSys
func (scriptList scriptList) getLangSys(scriptTag ScriptTag, languageTag LanguageTag) (langSys, bool) {
script, ok := scriptList[scriptTag]
if !ok || scriptTag == UnknownScript {
script, ok = scriptList[DefaultScript]
if !ok {
return langSys{}, false
}
}
langSys, ok := script[languageTag]
if !ok || languageTag == UnknownLanguage {
langSys = script[DefaultLanguage] // always present
}
return langSys, true
}
func (sfnt *SFNT) parseScriptList(b []byte) (scriptList, error) {
r := NewBinaryReader(b)
r2 := NewBinaryReader(b)
r3 := NewBinaryReader(b)
scriptCount := r.ReadUint16()
scripts := make(scriptList, scriptCount)
for i := 0; i < int(scriptCount); i++ {
scriptTag := ScriptTag(r.ReadString(4))
scriptOffset := r.ReadUint16()
r2.Seek(uint32(scriptOffset))
defaultLangSysOffset := r2.ReadUint16()
langSysCount := r2.ReadUint16()
langSyss := make(map[LanguageTag]langSys, langSysCount)
for j := -1; j < int(langSysCount); j++ {
var langSysTag LanguageTag
var langSysOffset uint16
if j == -1 {
langSysTag = DefaultLanguage // permanently reserved and cannot be used in font
langSysOffset = defaultLangSysOffset
} else {
langSysTag = LanguageTag(r2.ReadString(4))
langSysOffset = r2.ReadUint16()
if langSysTag == DefaultLanguage {
return scripts, fmt.Errorf("bad language tag")
}
}
r3.Seek(uint32(scriptOffset) + uint32(langSysOffset))
lookupOrderOffset := r3.ReadUint16()
if lookupOrderOffset != 0 {
return scripts, fmt.Errorf("lookupOrderOffset must be NULL")
}
requiredFeatureIndex := r3.ReadUint16()
featureIndexCount := r3.ReadUint16()
featureIndices := make([]uint16, featureIndexCount)
for k := 0; k < int(featureIndexCount); k++ {
featureIndices[k] = r3.ReadUint16()
}
langSyss[langSysTag] = langSys{
requiredFeatureIndex: requiredFeatureIndex,
featureIndices: featureIndices,
}
}
scripts[scriptTag] = langSyss
}
return scripts, nil
}
////////////////////////////////////////////////////////////////
type featureList struct {
tag []FeatureTag
feature [][]uint16
}
func (featureList featureList) get(i uint16) (FeatureTag, []uint16, error) {
if int(i) < len(featureList.tag) {
return featureList.tag[i], featureList.feature[i], nil
}
return UnknownFeature, nil, fmt.Errorf("invalid feature index")
}
func (sfnt *SFNT) parseFeatureList(b []byte) featureList {
r := NewBinaryReader(b)
r2 := NewBinaryReader(b)
featureCount := r.ReadUint16()
tags := make([]FeatureTag, featureCount)
features := make([][]uint16, featureCount)
for i := uint16(0); i < featureCount; i++ {
featureTag := FeatureTag(r.ReadString(4))
featureOffset := r.ReadUint16()
r2.Seek(uint32(featureOffset))
_ = r2.ReadUint16() // featureParamsOffset
lookupIndexCount := r2.ReadUint16()
lookupListIndices := make([]uint16, lookupIndexCount)
for j := 0; j < int(lookupIndexCount); j++ {
lookupListIndices[j] = r2.ReadUint16()
}
tags[i] = featureTag
features[i] = lookupListIndices
}
return featureList{
tag: tags,
feature: features,
}
}
////////////////////////////////////////////////////////////////
type lookup struct {
lookupType uint16
lookupFlag uint16
subtable [][]byte
markFilteringSet uint16
}
type lookupList []lookup
func (sfnt *SFNT) parseLookupList(b []byte) lookupList {
r := NewBinaryReader(b)
r2 := NewBinaryReader(b)
lookupCount := r.ReadUint16()
lookups := make(lookupList, lookupCount)
for i := 0; i < int(lookupCount); i++ {
lookupOffset := r.ReadUint16()
r2.Seek(uint32(lookupOffset))
lookups[i].lookupType = r2.ReadUint16()
lookups[i].lookupFlag = r2.ReadUint16()
subtableCount := r2.ReadUint16()
lookups[i].subtable = make([][]byte, subtableCount)
for j := 0; j < int(subtableCount); j++ {
subtableOffset := r2.ReadUint16()
lookups[i].subtable[j] = b[lookupOffset+subtableOffset:]
}
lookups[i].markFilteringSet = r2.ReadUint16()
}
return lookups
}
////////////////////////////////////////////////////////////////
type featureVariationsList struct {
Data []byte
}
////////////////////////////////////////////////////////////////
type coverageTable interface {
Index(uint16) (uint16, bool)
}
type coverageFormat1 struct {
glyphArray []uint16
}
func (table *coverageFormat1) Index(glyphID uint16) (uint16, bool) {
for i, coverageGlyphID := range table.glyphArray {
if coverageGlyphID < glyphID {
break
} else if coverageGlyphID == glyphID {
return uint16(i), true
}
}
return 0, false
}
type coverageFormat2 struct {
startGlyphID []uint16
endGlyphID []uint16
startCoverageIndex []uint16
}
func (table *coverageFormat2) Index(glyphID uint16) (uint16, bool) {
for i := 0; i < len(table.startGlyphID); i++ {
if table.endGlyphID[i] < glyphID {
break
} else if table.startGlyphID[i] <= glyphID {
return table.startCoverageIndex[i] + glyphID - table.startGlyphID[i], true
}
}
return 0, false
}
func (sfnt *SFNT) parseCoverageTable(b []byte) (coverageTable, error) {
r := NewBinaryReader(b)
coverageFormat := r.ReadUint16()
if coverageFormat == 1 {
glyphCount := r.ReadUint16()
glyphArray := make([]uint16, glyphCount)
for i := 0; i < int(glyphCount); i++ {
glyphArray[i] = r.ReadUint16()
}
return &coverageFormat1{
glyphArray: glyphArray,
}, nil
} else if coverageFormat == 2 {
rangeCount := r.ReadUint16()
startGlyphIDs := make([]uint16, rangeCount)
endGlyphIDs := make([]uint16, rangeCount)
startCoverageIndices := make([]uint16, rangeCount)
for i := 0; i < int(rangeCount); i++ {
startGlyphIDs[i] = r.ReadUint16()
endGlyphIDs[i] = r.ReadUint16()
startCoverageIndices[i] = r.ReadUint16()
}
return &coverageFormat2{
startGlyphID: startGlyphIDs,
endGlyphID: endGlyphIDs,
startCoverageIndex: startCoverageIndices,
}, nil
}
return nil, fmt.Errorf("bad coverage table format")
}
////////////////////////////////////////////////////////////////
type classDefTable interface {
Get(uint16) uint16
}
type classDefFormat1 struct {
startGlyphID uint16
classValueArray []uint16
}
func (table *classDefFormat1) Get(glyphID uint16) uint16 {
if table.startGlyphID <= glyphID && glyphID-table.startGlyphID < uint16(len(table.classValueArray)) {
return table.classValueArray[glyphID-table.startGlyphID]
}
return 0
}
type classRangeRecord struct {
startGlyphID uint16
endGlyphID uint16
class uint16
}
type classDefFormat2 []classRangeRecord
func (table classDefFormat2) Get(glyphID uint16) uint16 {
for _, classRange := range table {
if glyphID < classRange.startGlyphID {
break
} else if classRange.startGlyphID <= glyphID && glyphID <= classRange.endGlyphID {
return classRange.class
}
}
return 0
}
func (sfnt *SFNT) parseClassDefTable(b []byte, classCount uint16) (classDefTable, error) {
r := NewBinaryReader(b)
classFormat := r.ReadUint16()
if classFormat == 1 {
startGlyphID := r.ReadUint16()
glyphCount := r.ReadUint16()
classValueArray := make([]uint16, glyphCount)
for i := 0; i < int(glyphCount); i++ {
classValueArray[i] = r.ReadUint16()
if classCount <= classValueArray[i] {
return nil, fmt.Errorf("bad class value")
}
}
return &classDefFormat1{
startGlyphID: startGlyphID,
classValueArray: classValueArray,
}, nil
} else if classFormat == 2 {
classRangeCount := r.ReadUint16()
classRangeRecords := make(classDefFormat2, classRangeCount)
for i := 0; i < int(classRangeCount); i++ {
classRangeRecords[i].startGlyphID = r.ReadUint16()
classRangeRecords[i].endGlyphID = r.ReadUint16()
classRangeRecords[i].class = r.ReadUint16()
if classCount <= classRangeRecords[i].class {
return nil, fmt.Errorf("bad class value")
}
}
return classRangeRecords, nil
}
return nil, fmt.Errorf("bad class definition table format")
}
////////////////////////////////////////////////////////////////
type ValueRecord struct {
XPlacement int16
YPlacement int16
XAdvance int16
YAdvance int16
XPlaDeviceOffset uint16
YPlaDeviceOffset uint16
XAdvDeviceOffset uint16
YAdvDeviceOffset uint16
}
func (sfnt *SFNT) parseValueRecord(r *BinaryReader, valueFormat uint16) (valueRecord ValueRecord) {
if valueFormat == 0 {
return
} else if valueFormat&0x0001 != 0 { // X_PLACEMENT
valueRecord.XPlacement = r.ReadInt16()
} else if valueFormat&0x0002 != 0 { // Y_PLACEMENT
valueRecord.YPlacement = r.ReadInt16()
} else if valueFormat&0x0004 != 0 { // X_ADVANCE
valueRecord.XAdvance = r.ReadInt16()
} else if valueFormat&0x0008 != 0 { // Y_ADVANCE
valueRecord.YAdvance = r.ReadInt16()
} else if valueFormat&0x0010 != 0 { // X_PLACEMENT_DEVICE
valueRecord.XPlaDeviceOffset = r.ReadUint16()
} else if valueFormat&0x0020 != 0 { // Y_PLACEMENT_DEVICE
valueRecord.YPlaDeviceOffset = r.ReadUint16()
} else if valueFormat&0x0040 != 0 { // X_ADVANCE_DEVICE
valueRecord.XAdvDeviceOffset = r.ReadUint16()
} else if valueFormat&0x0080 != 0 { // Y_ADVANCE_DEVICE
valueRecord.YAdvDeviceOffset = r.ReadUint16()
}
return
}
////////////////////////////////////////////////////////////////
type singlePosTables []singlePosTable
func (tables singlePosTables) Get(glyphID uint16) (ValueRecord, bool) {
for _, table := range tables {
if valueRecord, ok := table.Get(glyphID); ok {
return valueRecord, true
}
}
return ValueRecord{}, false
}
type singlePosTable interface {
Get(uint16) (ValueRecord, bool)
}
type singlePosFormat1 struct {
coverageTable
valueRecord ValueRecord
}
func (table *singlePosFormat1) Get(glyphID uint16) (ValueRecord, bool) {
if _, ok := table.Index(glyphID); ok {
return table.valueRecord, true
}
return ValueRecord{}, false
}
type singlePosFormat2 struct {
coverageTable
valueRecord []ValueRecord
}
func (table *singlePosFormat2) Get(glyphID uint16) (ValueRecord, bool) {
if i, ok := table.Index(glyphID); ok {
return table.valueRecord[i], true
}
return ValueRecord{}, false
}
func (sfnt *SFNT) parseSinglePosTable(b []byte) (interface{}, error) {
r := NewBinaryReader(b)
posFormat := r.ReadUint16()
coverageOffset := r.ReadUint16()
coverageTable, err := sfnt.parseCoverageTable(b[coverageOffset:])
if err != nil {
return nil, err
}
valueFormat := r.ReadUint16()
if posFormat == 1 {
valueRecord := sfnt.parseValueRecord(r, valueFormat)
return &singlePosFormat1{
coverageTable: coverageTable,
valueRecord: valueRecord,
}, nil
} else if posFormat == 2 {
valueCount := r.ReadUint16()
valueRecord := make([]ValueRecord, valueCount)
for i := 0; i < int(valueCount); i++ {
valueRecord[i] = sfnt.parseValueRecord(r, valueFormat)
}
return &singlePosFormat2{
coverageTable: coverageTable,
valueRecord: valueRecord,
}, nil
}
return nil, fmt.Errorf("bad single adjustment positioning table format")
}
////////////////////////////////////////////////////////////////
type pairPosTables []pairPosTable
func (tables pairPosTables) Get(glyphID1, glyphID2 uint16) (ValueRecord, ValueRecord, bool) {
for _, table := range tables {
if valueRecord1, valueRecord2, ok := table.Get(glyphID1, glyphID2); ok {
return valueRecord1, valueRecord2, true
}
}
return ValueRecord{}, ValueRecord{}, false
}
type pairPosTable interface {
Get(uint16, uint16) (ValueRecord, ValueRecord, bool)
}
type pairValueRecord struct {
secondGlyph uint16
valueRecord1 ValueRecord
valueRecord2 ValueRecord
}
type pairPosFormat1 struct {
coverageTable
pairSet [][]pairValueRecord
}
func (table *pairPosFormat1) Get(glyphID1, glyphID2 uint16) (ValueRecord, ValueRecord, bool) {
if i, ok := table.Index(glyphID1); ok {
for j := 0; j < len(table.pairSet[i]); j++ {
if table.pairSet[i][j].secondGlyph == glyphID2 {
return table.pairSet[i][j].valueRecord1, table.pairSet[i][j].valueRecord2, true
} else if glyphID2 < table.pairSet[i][j].secondGlyph {
break
}
}
}
return ValueRecord{}, ValueRecord{}, false
}
type class2Record struct {
valueRecord1 ValueRecord
valueRecord2 ValueRecord
}
type pairPosFormat2 struct {
coverageTable
classDef1 classDefTable
classDef2 classDefTable
class1Records [][]class2Record
}
func (table *pairPosFormat2) Get(glyphID1, glyphID2 uint16) (ValueRecord, ValueRecord, bool) {
if _, ok := table.Index(glyphID1); ok {
class1 := table.classDef1.Get(glyphID1)
class2 := table.classDef1.Get(glyphID2)
return table.class1Records[class1][class2].valueRecord1, table.class1Records[class1][class2].valueRecord2, true
}
return ValueRecord{}, ValueRecord{}, false
}
func (sfnt *SFNT) parsePairPosTable(b []byte) (interface{}, error) {
r := NewBinaryReader(b)
r2 := NewBinaryReader(b)
posFormat := r.ReadUint16()
coverageOffset := r.ReadUint16()
coverageTable, err := sfnt.parseCoverageTable(b[coverageOffset:])
if err != nil {
return nil, err
}
valueFormat1 := r.ReadUint16()
valueFormat2 := r.ReadUint16()
if posFormat == 1 {
pairSetCount := r.ReadUint16()
pairSet := make([][]pairValueRecord, pairSetCount)
for i := 0; i < int(pairSetCount); i++ {
pairSetOffset := r.ReadUint16()
r2.Seek(uint32(pairSetOffset))
pairValueCount := r2.ReadUint16()
pairValueRecords := make([]pairValueRecord, pairValueCount)
for j := 0; j < int(pairValueCount); j++ {
pairValueRecords[j].secondGlyph = r2.ReadUint16()
pairValueRecords[j].valueRecord1 = sfnt.parseValueRecord(r2, valueFormat1)
pairValueRecords[j].valueRecord2 = sfnt.parseValueRecord(r2, valueFormat2)
}
pairSet[i] = pairValueRecords
}
return &pairPosFormat1{
coverageTable: coverageTable,
pairSet: pairSet,
}, nil
} else if posFormat == 2 {
classDef1Offset := r.ReadUint16()
classDef2Offset := r.ReadUint16()
class1Count := r.ReadUint16()
class2Count := r.ReadUint16()
classDef1, err := sfnt.parseClassDefTable(b[classDef1Offset:], class1Count)
if err != nil {
return nil, err
}
classDef2 := classDef1
if classDef1Offset != classDef2Offset {
if classDef2, err = sfnt.parseClassDefTable(b[classDef2Offset:], class2Count); err != nil {
return nil, err
}
}
class1Records := make([][]class2Record, class1Count)
for j := 0; j < int(class1Count); j++ {
class1Records[j] = make([]class2Record, class2Count)
for i := 0; i < int(class2Count); i++ {
class1Records[j][i].valueRecord1 = sfnt.parseValueRecord(r, valueFormat1)
class1Records[j][i].valueRecord2 = sfnt.parseValueRecord(r, valueFormat2)
}
}
return &pairPosFormat2{
coverageTable: coverageTable,
classDef1: classDef1,
classDef2: classDef2,
class1Records: class1Records,
}, nil
}
return nil, fmt.Errorf("bad single adjustment positioning table format")
}
////////////////////////////////////////////////////////////////
type gposTable struct {
scriptList
featureList
lookupList
featureVariationsList
tables []interface{}
}
func (table *gposTable) GetLookups(script ScriptTag, language LanguageTag, features []FeatureTag) ([]interface{}, error) {
var featureIndices []uint16
if langSys, ok := table.scriptList.getLangSys(script, language); ok {
featureIndices = append([]uint16{langSys.requiredFeatureIndex}, langSys.featureIndices...)
}
var lookupIndices []uint16
for _, feature := range featureIndices {
tag, lookups, err := table.featureList.get(feature)
if err != nil {
return nil, err
}
for _, selectedTag := range features {
if selectedTag == tag {
// insert to list and sort
InsertLoop:
for _, lookup := range lookups {
for i, lookupIndex := range lookupIndices {
if lookupIndex < lookup {
lookupIndices = append(lookupIndices[:i], append([]uint16{lookup}, lookupIndices[i:]...)...)
} else if lookupIndex == lookup {
break InsertLoop
}
}
}
break
}
}
}
tables := make([]interface{}, len(lookupIndices))
for i := 0; i < len(lookupIndices); i++ {
tables[i] = table.tables[lookupIndices[i]]
}
return tables, nil
}
func (sfnt *SFNT) parseGPOS() error {
b, ok := sfnt.Tables["GPOS"]
if !ok {
return fmt.Errorf("GPOS: missing table")
} else if len(b) < 32 {
return fmt.Errorf("GPOS: bad table")
}
sfnt.Gpos = &gposTable{}
r := NewBinaryReader(b)
majorVersion := r.ReadUint16()
minorVersion := r.ReadUint16()
if majorVersion != 1 && minorVersion != 0 && minorVersion != 1 {
return fmt.Errorf("GPOS: bad version")
}
var err error
scriptListOffset := r.ReadUint16()
if len(b)-2 < int(scriptListOffset) {
return fmt.Errorf("GPOS: bad scriptList offset")
}
sfnt.Gpos.scriptList, err = sfnt.parseScriptList(b[scriptListOffset:])
if err != nil {
return fmt.Errorf("GPOS: %w", err)
}
featureListOffset := r.ReadUint16()
if len(b)-2 < int(featureListOffset) {
return fmt.Errorf("GPOS: bad featureList offset")
}
sfnt.Gpos.featureList = sfnt.parseFeatureList(b[featureListOffset:])
lookupListOffset := r.ReadUint16()
if len(b)-2 < int(lookupListOffset) {
return fmt.Errorf("GPOS: bad lookupList offset")
}
sfnt.Gpos.lookupList = sfnt.parseLookupList(b[lookupListOffset:])
subtableMap := map[uint16]func([]byte) (interface{}, error){
1: sfnt.parseSinglePosTable,
2: sfnt.parsePairPosTable,
}
sfnt.Gpos.tables = make([]interface{}, len(sfnt.Gpos.lookupList))
for j, lookup := range sfnt.Gpos.lookupList {
if parseSubtable, ok := subtableMap[lookup.lookupType]; ok {
tables := make([]interface{}, len(lookup.subtable))
for i, data := range lookup.subtable {
var err error
tables[i], err = parseSubtable(data)
if err != nil {
return fmt.Errorf("GPOS: %w", err)
}
}
sfnt.Gpos.tables[j] = tables
} else if lookup.lookupType == 0 || 9 < lookup.lookupType {
return fmt.Errorf("bad lookup table type")
}
}
var featureVariationsOffset uint32
if minorVersion == 1 {
featureVariationsOffset = r.ReadUint32()
if len(b)-8 < int(featureVariationsOffset) {
return fmt.Errorf("GPOS: bad featureVariations offset")
}
sfnt.Gpos.featureVariationsList = featureVariationsList{b[featureVariationsOffset:]}
}
return nil
}